The invention relates to diesel-type injection pump assemblies and more particularly to facilities in such assemblies for securing a hollow cylinder head in pressure-tight fashion within the working cylinder of the pump assembly.
In known pump assemblies of this type, a cylinder head, which defines the upper portion of the working space of the piston carried in the cylinder, supports a conventional discharge valve in its lower end. The upper end of the cylinder head normally carries a threaded fitting for attachment to a pressure conduit.
Because of extremely high pressures generated in the portion of the cylinder adjacent the lower end of the cylinder head, it is necessary to provide efficient sealing between the head and the surrounding cylinder. In the past, such seals have involved the use of accurate threaded connections between the cylinder head and the cylinder, and/or the provision of washers or gaskets.
Each of such expedients has had disadvantages. In particular, the thread-type connection between head and cylinder has been found to deform the associated portion of the cylinder, and to shorten its life. Moreover, in extremely high-pressure applications, the gaskets or washers are also deformed and quickly lose their pressure-sealing properties.